usb2: no sound with M-Audio Transit

Hans Petter Selasky hselasky at c2i.net
Fri Nov 14 13:19:28 PST 2008


Hi Guys,

Has 24-bit audio ever been tested with USB Audio devices ?

There might be a problem with 16-bit to 24-bit conversion.

Does the PCM layer use 32-bits of data to store the 24-bits ?

What about buffer sizes?

Are all buffers modulo 3 when using 24-bit data?

--HPS

On Friday 14 November 2008, Stefan Ehmann wrote:
> On Friday 14 November 2008 18:11:23 Hans Petter Selasky wrote:
> > On Friday 14 November 2008, Stefan Ehmann wrote:
> > > http://stud4.tuwien.ac.at/~e0125637/fbsd/transit_config.dump
> >
> > Maybe there is something wrong with the 16-bit to 24-bit data conversion
> > ?
> >
> > Try to change:
> >
> > static uint8_t uaudio_default_bits = 32;
> >
> > to:
> >
> > static uint8_t uaudio_default_bits = 16;
> >
> > In:
> >
> > src/sys/dev/usb2/sound/uaudio2.c
> >
> > Then recompile and re-install "uaudio2.c".
>
> Great, now it sounds like actual music :)
>
> It now shows up as 48000Hz/16bit in dmesg.
>
> The mic mixer device seems to be what shows up as speaker in the old
> driver.



More information about the freebsd-multimedia mailing list